(a) Field of the Invention
The present invention relates to a digital still camera, and more particularly, to a digital still camera that uses a progressive image sensor.
(b) Description of the Related Art
FIG. 1 is a block diagram of a conventional digital still camera. As shown in FIG. 1, a lens unit 1 forms an image and directs it toward an image sensor/driving unit 3. The image sensor/driving unit 3 converts the light signals into corresponding electric signals.
The electric signals are applied to an analog/digital converter 5 and converted to digital image signals, which, in turn, are converted to digital color image data by an image sensor signal/color signal processing unit 7.
A lens driving/controlling unit 9 controls zooming, focusing, and the iris of lens unit 1. A control unit 11 controls operation of the entire system.
The digital color image data from the image sensor signal/color signal processing unit 7 is stored in a frame memory/strip memory 13. The frame memory/strip memory 13 includes a frame memory for storing one or more images and a strip memory for storing each line of the frame image. The data stored in the frame memory/strip memory 13 is applied to still image compression/decompression unit 15. The still image compression/decompression unit 15 compresses each still image stored in the frame memory/strip memory 13 and sends the compressed data to an image recording memory unit 17. The image recording memory unit 17 stores the compressed data.
The compressed data stored in the image recording memory unit 17 is decompressed by the still image compression/decompression unit 15, as needed. The decompressed data is applied to the image sensor signal/color signal processing unit 7 through the frame memory/strip memory 13. The image sensor signal/color signal processing unit 7 converts the decompressed data to digital image data, which are applied to a digital/analog converter 19 and converted to analog image signals. An image filter 21 generates analog color image signals from the analog image signals.
The compressed data stored in the image recording memory unit 17 is also transmitted to a computer through a computer interface unit 23.
As described above, the conventional digital still camera of prior art has to store a frame of digital image data in the frame memory 13 for data compression because the image sensor of the conventional digital still camera generates the image field-by-field in an interlace mode. The image data either needs to be stored in the frame memory unit 13 for compression, or the data must be compressed at the interlace speed.
A conventional digital still camera of the prior art uses the frame memory as a time delay because it employs an image sensor that is designed to output sequential images continuously. However, the increased number of pixels requires a large frame memory, which increases the cost of the camera.